The only thing that stands between China and its ambition to co-opt the Mekong as its own is opposition by Thai grassroots activists.
For decades, China has desired and designed to turn the river into a canal for its own boats from Yunnan.
In the early 2000s, it blasted 11 rapids and 10 reefs in the Mekong between Myanmar and Laos. Only one last islet remained in that first phase of operation. It's known as Khon Phi Long -- "the Islet of Lost Souls" -- a relatively large islet in the river between Laos and Thailand.
Wasant Techawongtham is former News Editor, Bangkok Post.
Grassroots activist groups made so much noise at the time that then prime minister Thaksin Shinawatra was persuaded to suspend the blasting on the grounds that it would have altered the Thai-Lao boundary demarcation in the middle of the river.
Even so, the Chinese operation was sufficiently successful that boats of 100-to-150-tonne displacement from Yunnan could reach port at Chiang Saen in Chiang Rai province.
Water released by Chinese-built dams on the Lancang, as China calls the upstream Mekong River, made the journey by these boats possible, even in the dry season.
The second phase of the project -- called the Development Plan for International Navigation on the Lancang-Mekong River (2015-2025) -- requires rock blasting along a 1.6km stretch of Thailand's Mekong border with Laos.
It will enable larger cargo boats of 500-tonne displacement to travel from Yunnan to the ancient Lao capital of Luang Prabang 630km downstream.
On Dec 27 last year, a cabinet resolution gave the nod to the project. That action set off a flurry of protest activities by Thai civil society groups.
Junta officials assured the public that approval was only granted for the river survey. But that supposedly innocuous action has effectively allowed the Chinese to plant a foot firmly in the door.
Prior to that, the Chinese made an unprecedented move by requesting to meet with Thai activists to assure them that their environmental concerns would be given serious consideration. The meeting resolved nothing.
While the activists oppose the Chinese plan mainly on conservation grounds, some academics and local business people have pointed out that Thailand has little to gain from the project.
Trade along the Chiang Saen-Chiang Khong border represents only 3% of total cross-border trade, said Saowaruj Rattanakhamfu, a senior economist at the Thailand Development Research Institute.
She said the Chinese could transport goods just as economically or more so through the new highway link through Laos without sacrificing the riverine ecosystem.
Local business people say Thai-Chinese trade on the Mekong is practically a one-way deal in favour of China. If Thai traders want to transport goods to China on the Mekong, they will need to ask Chinese authorities to release water from their dams, a step that is both inconvenient and unreliable.
What the business people say highlights what amounts to Chinese hypocrisy toward their neighbours, specifically in relation to the Mekong. That starts with its view that the Lancang is a Chinese river and the Mekong is a shared river. Such a view defines how it treats the river and its riparian neighbours.
When China built a cascade of dams on the Mekong, it consulted none of the downstream countries that are directly impacted. It shares no information about the volume of water behind these dams or how it is managed.
The dams changed everything in the river and not for the better. Riverside villagers and fishers have to live with uncertainties because of the unpredictable rise and fall of the river. The havoc it wreaks with plants and animals and the river's ecosystem in general is immeasurable.
Now that the Chinese need to use the downstream Mekong for their own purposes, they suddenly demand cooperation from neighbours. And cooperation they've got for the most part.
The Chinese have chosen the right time to launch the second phase of the project. Thailand's Indochinese neighbours have their own reasons to keep mum thus far while Thailand is ruled by a military junta that has gravitated toward China since taking power.
Thai Prime Minister Prayut Chan-o-cha and his cohorts would have no qualms if the Mekong ecosystem and riverside residents' livelihoods were destroyed so long as their own ambitions and possibly geopolitical and economic objectives are served.
But for the pesky Thai activists China would have smooth sailing.
However, the junta could apply its special power to subdue opposition and allow the project to proceed full steam ahead, if it so wishes.
Before it decides to do so, though, it has to ponder what would happen if the rock blasting changes the course of the river and thus the Thai-Lao boundary in favour of Laos?
No one, not even the Chinese with all their expertise and technology, can accurately predict the outcome.
Gen Prayut and friends could not shoulder the responsibility for the negative consequences on this score even if they man up to it.
And while the professed purposes of this project are trade and tourism promotion, there's another motive that none of the concerned countries have openly discussed.
Navigational access to the Mekong would allow China to project its power in the region more convincingly. That means Thailand would be drawn inexorably into the Chinese sphere of influence even more deeply than now.
Are the Thai military and public comfortable with that scenario?